The concern over acquired immune deficiency syndrome (AIDS) and other infectious diseases such as hepatitis has resulted in a number of protective devices designed to prevent accidental puncture to clinical personnel after use of a medical needle. Most of the protective devices have been developed for hypodermic needles as opposed to needles of the type to which the present invention relates. Medical apparatus employing needles of the type to which the present invention relates typically comprise a hollow inner needle which has a cutting or pointed edge for puncture and a concentric cylindrical device which slidingly receives the hollow needle. Typically, the outer cylindrical device is a catheter although the outer device could be the outer cannula of a biopsy needle. In needles of this type, the puncture is made with one hand similar to that of a hypodermic needle, but the withdrawal of the needle from the puncture site is made with two hands thus raising the likelihood of accidental needle puncture resulting from clinical personnel holding the catheter in a precise position while the needle is withdrawn.
The prior art has recognized the difficulties associated with catheters and has developed fail safe, puncture-proof devices as disclosed in the '516 and '718 patents incorporated by reference herein. Basically, the prior art devices modify the needle so that the needle is encased in a telescoping tubular arrangement. The needle conventionally punctures the patient's skin in a non-telescoped position. To withdraw the needle after puncture, the clinician grabs one end of the device while retracting the handle portion to telescope the handle so that the needle when withdrawn is retained within the expanded handle.
The prior art devices are effective but have not achieved wide scale commercial success principally because the cost of constructing a long, two-piece telescoping handle arrangement, even with relatively inexpensive plastics, materially increases the cost of the device compared to conventional, unshielded catheter needles. In addition, the prior art protective needles are more cumbersome to operate which may or may not be overcome with familiarity. Basically, the clinician prefers to advance the catheter with one hand while the needle is withdrawn with the other hand. In the prior art devices, the clinician must hold the telescoping barrel, sometimes by special or awkwardly placed tabs on the barrel. Although the barrel is fitted to the catheter hub, the point is that the attention of the clinician is focused away from the catheter while the needle is removed and the hand position is somewhat awkward. This can present problems in emergency situations, typically outside the confines of the hospital, where the catheter must be administered quickly.
To some extent the difficulties of the prior art described above are overcome somewhat by Corey '866 who discloses a removable protection guard for encapsulating the cutting edge of the needle after injection. However, Corey's protector guard is not easily removed from the catheter and does not positively lock the needle into the guard with the result that the device, in some instances, can be likely to cause an accidental puncture. Again, the clinician is familiar with utilizing a standard catheter and his attention is riveted onto making the injection and holding the needle in place while the catheter is advanced. Any protective device requiring some additional motion to actuate it or requiring attention to be directed away from the act of inserting and removing the needle is unsatisfactory.